Gardening Articles: Landscaping :: Lawns, Ground Cover, & Wildflowers

Garden Grinders

by Michael MacCaskey

I used to think that a chipper-shredder didn't make sense for anyone with less than a half-acre garden. But now that so many communities have banned or restricted disposal of yard waste, and because the cost of good compost and mulch keeps rising, I gave these machines a second look.

My own compost pile was "cold compost." I heaped all the yard waste in one pile and, given enough time, it would decompose. After shredding, my compost was another story altogether. Particles were smaller and more uniform, as you'd expect. More important, a mere two days later the temperature in the center of the pile shot up to 130oF, hot enough to destroy disease organisms and some weed seeds. My cold compost pile was reduced in volume by about half. It looked neater, and it got hot!

About Chippers and Shredders

Chippers and shredders for every size and type of garden (and gardener) are available. Several electric models are available that boast light weight, quiet operation, and low cost. At the other end of the spectrum are machines with 12 or more horsepower that can chip 4- to 6-inch limbs-and sometimes whole trees-but cost several thousand dollars. But for the purposes of this article, I chose to focus only on gasoline-powered chipper-shredders in the 5 to 10 horsepower range. They are medium to heavy-duty on the homeowner scale, and are I think, most likely to meet the expectations of avid gardeners. If you anticipate processing any woody branches or fibrous materials such as corn stalks, machines in this power range are essential.

For instance, one of the machines tested for this article, an 8-horsepower shredder-chipper, in about 2 hours reduced 2- to 3-inch-diameter stems pruned from a lilac, maple, and apple, into a small pile of chips.

While the heaviest of these avid gardener chipper-shredders, at 300 pounds, is a daunting piece of equipment, it and all the others listed here are mobile on their own wheels.

Following are descriptions of the main components all chipper-shredders have in common. Some models offer options such as electric engine starting, vacuum hoses, leaf tampers, and bagging kits.

Chipping Components

Chipping Blades. Most chipper-shredders have a chipping component that is separate from the shredding mechanism. You feed branches and similar woody material through a chipping tube where it contacts the chipping blade. The hardened steel blade quickly converts the woody material into chips or mulch. The chipper-shredders we looked at have one or two of these blades, and most are 3 to 4 inches long.

Manufacturers cite the diameter of the chipping tube as the "chipping capacity," which is fair enough because tube diameter is just slightly less than blade length. But it's a bit optimistic when it comes to hard, dry, or irregularly shaped wood. Conservatively, figure a chipper can handle branches that are half as wide as the chipper blade is long.

All but two machines utilize one or two rotor-mounted chipping blades. The exceptions, both from Troy-Bilt, are designed around a commercial-chipper-style, high-rpm drum mounted with two 8-inch blades. These machines are pure chippers, with no shredding hammers or screens. They can process limbs 5 to 6 inches in diameter, and anything else from your garden or yard, though particle size is larger and more irregular.

Chipper blades need sharpening or replacement from time to time. Feeding them soil and stones dulls them fast. Check with your manufacturer. Some chipper blades are reversible, a convenient feature that reduces both downtime and costs. Before buying, consider what's involved in replacing the blade, and plan on doing so at least annually.